This invention relates to a welding system, and more particularly, to one useful when applied in performing high accuracy butt welding.
In recent years, a material called a tailored blank, which is formed by butting a plurality of steel plates having the same plate thickness and comprising the same material or having different plate thicknesses and comprising different materials, and integrating them by CO2 (carbon dioxide gas) laser welding or the like, has been used as a molding material for a vehicle body panel of an automobile, etc.
When this type of tailored blank is used, tip materials, which have occurred as scrap during various pressing steps, can be used effectively, waste of the material is reduced, and the yield from the material is increased. When a tailored blank comprising a combination of a steel plate having a large plate thickness and a steel plate having a small plate thickness is used to mold a panel part of a predetermined shape, for example, other advantages are also obtained, such that weight reduction can be achieved compared with molding of the entire panel part from a single thick steel plate.
When a tailored blank is to be obtained by butt welding two steel plates, it is necessary to place on a table, which constitutes a horizontal surface, two steel plates to be butt welded, and either transport each steel plate toward a predetermined reference plate, or transport one of the steel plates toward the end surface of the other steel plate whose positioning has been completed upon its butting against the reference plate to butt the two steel plates against each other. Thus, a welding system for performing this type of tailored blank welding needs to have a transport device and a reference position locating mechanism for steel plates as materials to be welded.
When butt welding of materials to be welded is to be carried out, such as when a tailored blank is to be obtained by butt welding two steel plates, it is generally necessary to run a carriage bearing a welding head along a horizontal beam. By so doing, the welding head is moved along a weld line of a butt weld zone. From the viewpoint of the welding efficiency, it is desirable to move the welding head at a high speed. On the other hand, a demand for the accuracy of welding in a tradeoff relationship with the high moving speed is becoming harsh year by year.
In view of the above points, the preferred welding head for use in the welding system is a laser/arc combined welding head for simultaneous implementation of laser welding and arc welding which can perform welding with a large melting width (high groove tolerance) and a great penetration depth.
An example of this type of laser/arc combined welding head is a coaxial welding head proposed in Japanese Unexamined Patent Publication No. 1999-156573. The coaxial welding head (not shown) reflects laser light by a convex surface of a convex roof mirror to divide it into two beams, a first divisional laser beam and a second divisional laser beam, further reflects these divisional laser beams by a concave surface of a concave roof mirror to form a space portion between the first divisional laser beam and the second divisional laser beam, and places an arc electrode in this space portion to make the laser light and the arc electrode coaxial. This coaxial arrangement of the laser light and the arc electrode obtains the effect that the welding head can be downsized, and the effect that the welding head can be moved easily in an arbitrary direction.
However, when laser welding and arc welding are performed simultaneously using the laser/arc combined welding head according to the prior art, a metal vapor 05 generated by irradiation of a material 03 to be welded, such as a steel plate, with laser light 02 deposits on the tip of an arc electrode (arc rod) 01, as shown in FIG. 36.
Thus, the arc electrode 01 minimally discharges, or the deposited metal interferes with the laser light path to decrease the energy of the laser light 02. That is, from the point of view of applying an arc discharge reliably to the material 03 to be welded, the arc electrode 01 should be rendered as close as possible to a laser light irradiation position 03a of the material 03 to be welded. From the viewpoint of avoiding deposition of the metal vapor 05 on the tip of the arc electrode, the arc electrode 01 should be made as remote as possible from the laser light irradiation position 03a. 
Hence, it is desirable to set the arc electrode 01 at an optimal position which satisfies both of the above requirements. However, optimal conditions for placement have not been obtained, because of the lack of an arc electrode adjusting mechanism.
The present invention has been made in view of the above-described prior art. The object of the present invention is to provide a welding system which has a combined welding head capable of performing combined welding under optimal conditions for placement of an arc electrode relative to a laser light irradiation position while effectively preventing deposition of a metal vapor on the arc electrode, and which can perform butt welding, such as tailored blank welding, with high efficiency and high accuracy.
The constitutions of the present invention for attaining the above object are as follows:
I) A welding system comprising:
a welding stage having a table forming a horizontal surface on which materials to be welded are placed;
reference position locating means having a reference plate which is contacted by an end surface of one of the materials to be welded, while protruding upward from an upper surface of the table, to position the end surface of the plate material, prior to butt welding for butting the end surfaces of the materials to be placed on the upper surface of the table and welding the end surfaces together, and which retreats downward from the upper surface of the table during welding;
transport means for materials to be welded, adapted to transport the material to be welded, which has been placed on the upper surface of the table, toward the reference plate, or the end surface of the one of the materials to be welded whose positioning has been completed upon contact with the reference plate;
a horizontal beam supported at both ends by vertical end struts, and disposed horizontally like a bridge over the welding stage;
a carriage traveling horizontally on the horizontal beam; and
a welding head loaded on the carriage, and moved along a weld line together with the carriage to weld a weld area of the materials to be welded which have been placed on the welding stage, and wherein
the welding head is a laser/arc combined welding head for simultaneously performing laser light irradiation and arc discharge of the materials to be welded, thereby welding the materials to be welded, and
further includes arc electrode position adjusting means for moving an arc electrode in a direction perpendicular to a direction of an optical axis of laser light applied to the materials to be welded, thereby adjusting the position of the arc electrode in the perpendicular direction relative to the position of irradiation with laser light in the materials to be welded.
According to the present invention, the material to be welded, which has been transported by the transport means, is brought into contact with the reference plate of the reference position locating means, and positioned thereby, and then the end surface of the other material to be welded, which has been transported by other transport means, is brought into contact with the end surface of the positioned material to be welded, to complete preparations for butt welding. In this condition, butt welding can be performed using the laser/arc combined welding head which travels together with the carriage along the weld line running along a butt zone of the two materials to be welded. That is, positioning for butt welding of the materials to be welded, and butt welding can be carried out automatically as a series of operations.
In the butt welding, the arc electrode can be moved in the direction perpendicular to the direction of the optical axis of laser light applied to the materials to be welded. Thus, there can be selected optimal conditions for placement of the arc electrode at the position in the perpendicular position, namely, the optimal placement conditions under which the arc discharge to the materials to be welded can be performed reliably, and deposition of the metal vapor on the tip of the arc electrode can be prevented.
II) A welding system comprising:
a plurality of welding stages each having a table forming a horizontal surface on which materials to be welded are placed, and being disposed adjacent to each other;
a horizontal beam supported at both ends by vertical end struts, and disposed horizontally like a bridge over the welding stages;
an intermediate strut supporting an intermediate site of the horizontal beam between the adjacent welding stages;
a carriage traveling horizontally on the horizontal beam;
a plurality of reference position locating means each having a reference plate which is contacted by an end surface of one of the materials to be welded, while protruding upward from an upper surface of each table, to position the end surface of the material to be welded, prior to butt welding for butting the end surfaces of the materials placed on the upper surface of each table and welding the end surfaces together, and which retreats downward from the upper surface of each table during welding;
a plurality of transport means for materials to be welded, adapted to transport the material to be welded, which has been placed on the upper surface of each table, toward the reference plate, or the end surface of the one of the materials to be welded whose positioning has been completed upon contact with the reference plate;
a welding head loaded on the carriage, and moved along a weld line together with the carriage to weld a weld area of the materials to be welded which have been placed on the welding stages, and wherein
the welding head is a laser/arc combined welding head for simultaneously performing laser light irradiation and arc discharge of the materials to be welded, thereby welding the materials to be welded,
further includes arc electrode position adjusting means for moving an arc electrode in a direction perpendicular to a direction of an optical axis of laser light applied to the materials to be welded, thereby adjusting the position of the arc electrode in the perpendicular direction relative to the position of irradiation with laser light in the materials to be welded, and
is configured such that in accordance with movement in one direction of the carriage located at one of the ends of the horizontal beam as an initial position, the welding head welds the material, to be welded, on each welding stage at a predetermined welding speed, and upon completion of welding of the materials, to be welded, on all the stages as a result of movement to the other end of the horizontal beam, the welding head moves in the opposite direction at a higher speed than the welding speed, arrives at the initial position, and performs a predetermined welding operation while moving again toward the other end along the horizontal beam.
According to this invention, the materials, to be welded, on the plurality of welding stages can be butt welded by the single welding head traveling together with the single carriage, in addition to the effects of the invention described in I). Therefore, the efficiency of the welding operation increases dramatically. Furthermore, the horizontal beam on which the carriage moves can be converted to a rigid structure by use of the intermediate strut. Thus, even when the carriage on the horizontal beam moves at a high speed, associated vibrations of the horizontal beam can be suppressed, and the welding head can be fed accurately along the weld line. That is, the effect of achieving high speed movement of the carriage, and the effect of maintaining a high welding accuracy can be realized at the same time.
III) The welding system of II) above characterized in that
one weld state detection sensor for detecting whether the state of weld is good or poor is disposed on the carriage downstream from the welding head in a moving direction during welding.
According to this invention, the state of weld is detected only during movement of the welding head in one direction. As a result, only one weld state detection sensor, which is expensive, is used. Thus, cost reduction can be achieved.
IV) The welding system described in II) or III) above characterized in that
the carriage is moved by drive means and moving means composed of a pinion bonded to a rotating shaft of the drive means, and a rack disposed on an upper surface of the horizontal beam from one end to the other end of the upper surface and engaged with the pinion.
According to this invention, the moving parts, such as carriage and welding head, are moved by transmitting a rotating force to the rack via the pinion. The moving speed of the carriage can be made much higher than the use of a ball screw. Incidentally, the use of the ball screw gives a traveling speed of 110 m/mm at the highest, while the use of the rack and pinion can achieve a high speed of 240 m/min, when the moving part such as carriage weighs about 300 Kg.
In the welding systems described in I to IV) above, the welding head may be as follows:
1) A laser/arc combined welding head for simultaneously performing laser light irradiation and arc discharge of the materials to be welded, thereby welding the materials to be welded, and
further including arc electrode inclination angle adjusting means for inclining an arc electrode relative to a laser light irradiation position in the materials to be welded, thereby adjusting an inclination angle of the arc electrode relative to the laser light irradiation position.
According to this invention, there can be selected optimal conditions for placement of the arc electrode at the inclination angle, namely, the optimal placement conditions under which the arc discharge to the materials to be welded can be performed reliably, and deposition of the metal vapor on the tip of the arc electrode can be prevented.
2) A laser/arc combined welding head for simultaneously performing laser light irradiation and arc discharge of the materials to be welded, thereby welding the materials to be welded, and
further including arc electrode distance adjusting means for bringing an arc electrode close to or away from a laser light irradiation position in the materials to be welded, thereby adjusting a distance between the laser light irradiation position and the arc electrode.
According to this invention, there can be selected optimal conditions for placement in connection with the distance between the laser light irradiation position and the arc electrode, namely, the optimal placement conditions under which the arc discharge to the materials to be welded can be performed reliably, and deposition of the metal vapor on the tip of the arc electrode can be prevented.
3) A laser/arc combined welding head for simultaneously performing laser light irradiation and arc discharge of the materials to be welded, thereby welding the materials to be welded, and
further including an arc electrode adjusting mechanism composed of
arc electrode position adjusting means for moving an arc electrode in a direction perpendicular to a direction of an optical axis of laser light applied to the materials to be welded, thereby adjusting the position of the arc electrode in the perpendicular direction relative to a laser light irradiation position in the materials to be welded,
arc electrode inclination angle adjusting means for inclining the arc electrode relative to the optical axis of laser light, thereby adjusting the inclination angle of the arc electrode, and
arc electrode distance adjusting means for bringing the arc electrode close to or away from the laser light irradiation position in the materials to be welded, thereby adjusting a distance between the laser light irradiation position and the arc electrode.
According to this invention, meticulous adjustment for placement of the arc electrode is made by the arc electrode adjusting mechanism, thus making it possible to select optimal placement conditions under which the arc discharge to the materials to be welded can be performed reliably, and deposition of the metal vapor on the tip of the arc electrode can be prevented.
4) In the welding head of 3) above,
the arc electrode adjusting mechanism comprises
a pair of flange mounting surfaces formed parallel on both sides of a nozzle of the welding head, and having elongated holes elongated in the direction of the optical axis of laser light to be applied to the materials to be welded, opposite ends of an arc electrode support member being inserted through the elongated holes,
first flanges each having elongated holes elongated in the direction of the optical axis, being fixed to the flange mounting surface by screws via the elongated holes, having a hole of such a size that the arc electrode support member is tiltable, the opposite ends of the arc electrode support member being inserted through the holes,
first seal members each interposed between the flange mounting surface and the first flange, and surrounding the periphery of the elongated hole of the flange mounting surface,
second flanges each fixed to an outer surface of the first flange by screws, having a hole larger than the hole of the first flange for insertion of the opposite ends of the arc electrode support member, and having a protrusion in a portion outside the hole, the protrusion protruding inward over an entire periphery, having an inner periphery larger than an outer periphery of the arc electrode support member, and allowing the arc electrode support member to tilt, and
second seal members each disposed along an inner peripheral surface of the hole of the second flange to surround the outer periphery of the arc electrode support member, and squeezed by the protrusion of the second flange when the screws are tightened to fix the second flange to the first flange, thereby closing a gap between the arc electrode support member and the second flange, and fixing the arc electrode support member by a reaction force.
According to this invention, meticulous adjustment for placement of the arc electrode is made, thus making it possible to select optimal placement conditions under which the arc discharge to the materials to be welded can be performed reliably, and deposition of the metal vapor on the tip of the arc electrode can be prevented.
5) In the welding head of 3) above,
the arc electrode adjusting mechanism comprises
a support member for pivotably supporting an arc electrode support member,
a first vertical slide guide fixed to a side portion of a nozzle of the welding head,
a second vertical slide guide guided by the first vertical slide guide in the direction of the optical axis of laser light applied to the materials to be welded,
a cross feed screw screwed to the first vertical slide guide, and having a front end portion rotatably joined to the support member to move the arc electrode in the direction perpendicular to the direction of the optical axis together with the support member and the arc electrode support member,
a swing feed screw screwed to the first vertical slide guide, and having a front end portion rotatably and pivotably joined to the arc electrode support member to pivot the arc electrode together with the arc electrode support member, and
a vertical feed screw screwed to the first vertical slide guide, and having a front end in contact with a bottom surface of the second vertical slide guide to move the arc electrode in the direction of the optical axis together with the second vertical slide guide, the support member, and the arc electrode support member.
According to this invention, meticulous adjustment for placement of the arc electrode is made, thus making it possible to select optimal placement conditions under which the arc discharge to the materials to be welded can be performed reliably, and deposition of the metal vapor on the tip of the arc electrode can be prevented.
6) A laser/arc combined welding head for simultaneously performing laser light irradiation and arc discharge of the materials to be welded, thereby welding the materials to be welded, and
including gas flow generating means provided in a support portion of an arc electrode for generating and ejecting a gas flow along an axis of the arc electrode.
According to this invention, deposition of the metal vapor on the tip of the arc electrode can be reliably prevented, and satisfactory laser/arc combined welding can be performed.
7) Any of the welding heads described above,
including gas flow generating means provided in a support portion of an arc electrode for generating and ejecting a gas flow along an axis of the arc electrode.
According to this invention, optimal conditions for placement of the arc electrode can be selected, deposition of the metal vapor on the tip of the arc electrode can be reliably prevented, and satisfactory laser/arc combined welding can be performed.
8) A laser/arc combined welding head for simultaneously performing laser light irradiation and arc discharge of the materials to be welded, while disposing an arc electrode outside laser light, thereby welding the materials to be welded, and
further including gas flow generating means provided in a support portion of the arc electrode for generating and ejecting a gas flow along an axis of the arc electrode, with the arc electrode being disposed outside the laser light in the same welding head.
According to this invention, compactness of the welding apparatus can be achieved, deposition of the metal vapor on the tip of the arc electrode can be reliably prevented, and satisfactory laser/arc combined welding can be performed.
9) The welding head of 8) above, wherein
a plurality of the arc electrodes are attached to a ring-shaped support member, which surrounds the laser light, with predetermined spacing in a circumferential direction, and can be used selectively according to the direction of welding.
According to this invention, deposition of the metal vapor on the tip of the arc electrode can be reliably prevented, and satisfactory laser/arc combined welding can be performed.
10) A laser/arc combined welding head for simultaneously performing laser light irradiation and arc discharge of the materials to be welded, thereby welding the materials to be welded, wherein
an arc electrode is disposed downstream from a laser light irradiation position in a direction of movement of the welding head.
According to this invention, deposition of the metal vapor on the tip of the arc electrode can be reliably prevented, and satisfactory laser/arc combined welding can be performed.
11) A laser/arc combined welding head for simultaneously performing laser light irradiation and arc discharge of the materials to be welded, thereby welding the materials to be welded, wherein
an arc electrode is disposed downstream from a laser light irradiation position in a direction of movement of the welding head.
According to this invention, deposition of the metal vapor on the tip of the arc electrode can be reliably prevented, and satisfactory laser/arc combined welding can be performed.
The reference position locating means in the welding systems described in I) to IV) above is as follows:
12) The reference position locating means configured such that
a second table is divided so as to be contactable with or separable from a first table, the first table bearing one of the materials to be welded, and the second table bearing the other material to be welded which is butt welded to the one material to be welded,
in positioning the end surface of the one material to be welded, the reference plate is protruded upward from the upper surface of the first table, with the second table being separated from the first table, and
after completion of a positioning operation for the end surface of the one material to be welded, the reference plate is retreated downward from the upper surface of the first table, and the second table is moved toward the first table, whereupon its end surface contacts the end surface of the first table, thereby closing a space above the retreated reference plate.
According to this invention, the reference plate during welding can be retreated into the space closed upward. Consequently, welding powder during welding does not become an obstacle to the ascent and descent of the reference plate, and the positioning accuracy for the reference plate can be easily rendered sufficiently high.
13) The reference position locating means of 12) above, wherein
in a portion of contact between the first table and the second table, the end surface of one of the tables forms a protrusion protruding horizontally toward the end surface of the other table, and the end surface of the other table forms a concavity to be fitted with the protrusion.
According to this invention, welding can be performed, with the protrusion being fitted into the concavity. Thus, the space in which the reference plate has retreated can be completely separated from welding powder. Consequently, the effects of the invention described in 12) above can be obtained reliably.
14) The reference position locating means of 12) or 13) above, wherein
the reference plate is fastened to a front end portion of a lever rotating normally and reversely about a point below the upper surface of the first table as a center of rotation, and is constituted such that as the lever rotates in one direction, the reference plate rotates until the lever partly contacts the end surface of the first table to restrain the rotation, whereupon the reference plate protrudes above the upper surface of the first table, and as the lever rotates in the opposite direction, the reference plate retreats below the upper surface of the first table.
According to this invention, the reference table can be moved upward and downward by rotation of the lever. Consequently, the space for ascent and descent of the reference plate can be minimized. This leads to the effect that the space below the table, in which various instruments are arranged complexly, can be utilized effectively and rationally.
15) The reference position locating means of 14) above, wherein
the lever is rotated by driving of an air cylinder having a piston rod whose front end is connected to an intermediate site of the lever.
According to this invention, rotation of the lever can be made by extension and contraction of the piston rod. Consequently, the same effects as in 13) above can be expected, and these effects can be realized concretely.
16) The reference position locating means of 14) or 15) above, wherein
the end surface of a bolt screwed to the lever such that the amount of protrusion of the bolt from the end surface of the lever is adjustable contacts the end surface of the first table to restrain the rotation of the lever.
According to this invention, adjustment of the ascent position of the lever according to rotation is made by adjusting the amount of protrusion of the bolt. Consequently, mere adjustment of the bolt can result in the positioning of the reference plate, thus facilitating the adjusting operation.
The transport means in the welding systems described in I) to IV) described above is as follows:
17) The transport means has a plurality of transport arms, and is configured such that the plurality of transport arms are moved parallel toward a material to be welded, which is an odd-shaped member; each time a welded material detection sensor of each transport arm detects the material to be welded, drive means of the transport arm is driven to grasp an end portion of the material, to be welded, between an upper lever and a lower lever of the transport arm and detect a state of grasp by a grasp state detection sensor; and after a state of grasp by all the transport arms of the material to be welded is detected, each transport arm is moved parallel in the same amount to transport the material to be welded up to a predetermined position,
the transport arm includes
a bench having the welded material detection sensor at a front end thereof, and adapted to move toward the odd-shaped material to be welded,
the drive means disposed on the bench,
the lower lever caused to protrude forward from the bench by driving of the drive means, and rotating in one direction relative to the bench to contact the odd-shaped material, to be welded, from below the material to be welded, and
the upper lever caused to protrude forward from the bench, integrally with the lower lever, upon driving of the drive means, and rotating in the opposite direction relative to the bench to contact the material, to be welded, from above the material to be welded, and
after the welded material detection sensor detects the material to be welded, the upper lever and the lower lever are rotated, whereby the end portion of the material to be welded is grasped between the upper lever and the lower lever.
According to this invention, a predetermined grasping action is started when the plate material detection sensor senses the presence of the plate material, and the plate material can be grasped between the upper lever and the lower lever. Thus, no matter what shape the plate material has, the plate material can be grasped satisfactorily. That is, even if one of the materials to be butt welded is an odd-shaped plate material, this plate material can be butted automatically and satisfactorily against the welding end surface of the other material to be welded. Consequently, the welding system is a particularly useful system as a tailored blank welding apparatus for steel plates and as a butt welding apparatus for steel sheets.
The transport arm in 17) above may be configured as follows:
18) The transport arm of 17) above, wherein
the bench includes a horizontal base plate, a vertical member provided vertically on the base plate, and a support member protruding forward from the front end of the vertical member to support an odd-shaped plate material from below by a front end portion thereof and having a plate material detection sensor disposed for detecting the odd-shaped plate material, and the bench is also fastened to an air cylinder as drive means,
the air cylinder is adapted to extend or contract its piston rod in a horizontal direction to move a moving member, which is fastened to the front end of the piston rod, linearly in a horizontal direction on the base plate,
the lower lever has its base end portion attached pivotably to the moving member via a pin, and a pin disposed midway through the lower lever is fitted into an elongated hole provided in a longitudinal direction of the vertical member, whereby the lower level follows the shape of the elongated hole and moves as the moving member moves,
the upper lever is attached pivotably to a middle portion of the lower level via a pin, contacts a contact member of the bench according to forward movement of the moving member, and rotates toward the lower lever about the pin as a center of rotation in accordance with further forward movement,
according to forward movement toward the odd-shaped plate material, the plate material detection sensor detects the odd-shaped plate material,
at the position of detection, movement of the bench is stopped and the air cylinder is driven to move the moving member forward, and
according to this forward movement, the lower lever and the upper lever are rotated in opposite directions, whereby the end portion of the odd-shaped plate material is grasped between the upper lever and the lower lever.
According to this invention, simply by driving the air cylinder to extend its piston rod, thereby moving the moving member linearly, the lower lever acts to support the plate material from below. Moreover, the upper lever rotating upon contact with the contact member rotates from above and contacts the upper surface of the material to be welded, whereby the material to be welded can be grasped between the upper lever and the lower lever. Consequently, regardless of the shape of the material to be welded, this material can be grasped satisfactorily. This grasping action can be performed simply by driving of the air cylinder. Thus, the mechanism for the grasping action can be rendered most rational.
19) The transport arm of 17) or 18) above, wherein
a spring is provided between the upper lever and the lower lever, and the spring force of the spring is adjusted to adjust a grasping force for the odd-shaped material to be welded which is grasped between the upper lever and the lower lever.
According to this invention, the grasping force for the plate material grasped by the upper arm and the lower arm can be adjusted freely. As a result, when the material to be welded being grasped by the transport arms is butted against the other material to be welded, a slip occurs between the upper arm/lower arm and the material to be welded, so that some misalignment with the butt end surface of the material to be welded can be accommodated.